Method and system for controlling a CD-ROM drive in an operating system-independent reduced power mode

ABSTRACT

A portage computer case whether in a closed state or open state permits a user to exercise control and monitor certain operating features. The user may toggle a control switch to place the computer system in a secondary operational mode, determine when a computer system is in a secondary operational mode, and adjust a digital master volume control during the secondary operational mode. The portable computer system includes a status indicator for indicating when a computer is in a secondary operational mode, digital master volume control buttons operable in a secondary operational mode, and a control switch for placing the computer system in a secondary operational mode. The status indicator, volume control buttons, and control switch are preferably provided on a top surface of the bottom shell of the portable computer for convenient access by a user. As such, a user is capable of placing the computer system in a secondary operational mode and determining when the computer system is in a secondary operational mode without opening the portable computer case. A user is also capable of adjusting volume control during a secondary operation mode without the need to access a plurality of volume controls, sort through software to adjust the volumes of the audio sources, or open the portable computer case to visualize volume controls for the audio sources on the main display screen.

RELATED APPLICATIONS

This application is a continuation of Ser. No. 08/879,876, filed Jun.20, 1997 now U.S. Pat. No. 6,073,187.

This application is related to the following co-pending, commonly ownedUnited States Patent Application which is hereby incorporated byreferences.

U.S. patent application Ser. No. 08/846,641, filed on Apr. 30, 1997,entitled “COMPUTER SYSTEM CAPABLE OF PLAYING AUDIO CDS IN A CD-ROM DRIVEINDEPENDENT OF AN OPERATING SYSTEM,” to William E. Jacobs, Dan V.Forlenza, James L. Mondshine, Tim L. Zhang, Greg B. Memo, Kevin R.Frost, and Lonnie J. Pope now U.S. Pat. No. 6,006,285.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to controls and indicators, includingmaster volume control buttons, a status indicator, and a control switchfor a secondary operational mode of a computer system such as a mode forplaying audio CDs in a CD-ROM drive independent of an operating system.

2. Description of the Related Art

Operating a CD-ROM drive in a computer system has required booting anoperating system and loading and utilizing a CD-ROM drive application.The RAM-based CD-ROM device driver of the CD-ROM drive applicationallowed for operation of the CD-ROM drive. The lengthy duration of thebooting process for an operating system and the considerable userinteraction required by a CD-ROM drive application render playing anaudio CD in the CD-ROM drive of a computer system, as opposed to in aconventional audio CD player, undesirable. An audio CD player, unlike aCD-ROM drive of a computer system, does not involve a timelyinitialization process and substantial user interaction. As such,despite the CD-ROM drive present in conventional computer systems, usershave maintained a separate audio CD player in place of the portablecomputer. In addition, where a user is away from his or her audio CDplayer, a conventional computer system due to its initialization anduser interaction requirements is unsuited to playing an audio CD asquickly and easily as allowed by a conventional audio CD player. Becauseof the initialization process and user interaction required, portablecomputer users would often carry a separate audio CD player for musiclistening even though the portable computer had music playingcapability. Also, since a CD-ROM drive application was dependent upon anoperating system, it was necessary to use a display screen to visuallyindicate to the user when a CD-ROM drive application was being operated.As such, portable computer users have been required to maintain theportable computer case containing a portable computer in its open stateto determine the status of a CD-ROM drive application.

Further, a conventional computer system has required a user to accessnumerous locations, software and hardware, to adjust the volume andother settings of various audio sources such as a CD, wave, andsynthesizer for music listening. These locations typically include amixer in a Windows CD-ROM drive application for controlling the volumeof audio sources, a software master volume control in a Windows taskbar, and a hardware volume thumbwheel. As these volume control sourcescontrolled volume independent of each other, it was necessary for a userto sort through cumbersome CD-ROM drive software to adjust the volume ofthe appropriate audio sources. In light of the software nature ofcertain volume controls, it was also necessary to maintain the portablecomputer case in its open state with the display screen visible to auser to allow for certain volume adjustments during music listening.

SUMMARY OF THE INVENTION

With the present invention, a user is capable of accomplishing severalcontrol and monitoring functions whether a portable computer case ismaintained in a closed state or open state. These functions includetoggling a control switch to place the computer system in a secondaryoperational mode, determining when the computer system is in a secondaryoperational mode, and adjusting digital master volume control during thesecondary operational mode. The portable computer system of the presentinvention includes a status indicator for indicating when a computer isin a secondary operational mode, digital master volume control buttonsoperable in a secondary operational mode, and a control switch forplacing the computer system in a secondary operational mode. The statusindicator, master volume control buttons, and control switch arepreferably provided on the top surface of the bottom shell of theportable computer for convenient access by a user. Thus, a user is ableto of placing the computer system in a secondary operational mode anddetermining when the computer system is in a secondary operational modewithout opening the portable computer case. A user is able to adjustvolume control during a secondary operation mode without the need fortedious, cumbersome tasks, such as to access a plurality of volumecontrols, sort through software to adjust the volumes of the audiosources, or open the portable computer case to visualize volume controlsfor the audio sources on the computer's main display screen.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of the preferred embodiment is consideredin conjunction with the following drawings, in which:

FIG. 1 is a schematic diagram of a portable computer system showing anaudio CD mode ROM, audio CD mode switch, status indicator, and mastervolume control buttons of the present invention;

FIG. 2 is a diagram of the firmware code in the audio CD mode ROM ofFIG. 1 for the keyboard controller embodiment of the present invention;

FIG. 3 is a flow chart of the software initialization process forconfiguring the computer system of FIG. 1 for its master volume controlbuttons;

FIG. 4 is an isometric view of a portable computer case containing thecomputer system of FIG. 1 in an open state;

FIG. 5 is an isometric view of the portable computer case of FIG. 4 in aclosed state;

FIG. 6 is an enlarged plan view illustrating the portion of the topsurface of the bottom shell of the portable computer case of FIG. 4circled and having the numeral “6” designating same, showing in moredetail the status indicator, master volume control buttons, and audio CDmode switch;

FIG. 7 is a state diagram of the power control states of the computersystem of FIG. 1; and

FIG. 8 is a schematic electrical circuit diagram of the mini statusdisplay screen control circuitry of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning to FIG. 1, a schematic diagram of a portable computer system Sof the present invention is shown. Within the portable computer S, a CPU10 and a Level 2 (L2) cache 12 are connected. The processor 10 ispreferably a Pentium® processor manufactured by Intel Corporation ofSanta Clara, Calif. The processor 10 operates preferably with a standardIBM-PC compatible operating system, such as Windows 95, available fromMicroSoft Corporation of Redmond, Wash. The L2 cache 12 providesadditional caching capabilities to the processor's on-chip cache toimprove performance.

The CPU 10 and the L2 cache 12 are connected to a host/PCI bridge 14.Also connected to the host/PCI bridge 14 is a synchronous DRAM 16. Thehost/PCI bridge 14 is further coupled to a PCI bus P that connects to aPCMCIA/CardBus controller 18 and a video card 20 including a videographics controller and video memory. The video graphics controller ofcard 20 provides control signals to the main liquid crystal displayscreen 406 (FIGS. 1 and 4). The PCMCIA/CardBus controller 18 is alsocoupled to a set of PCMCIA cards 22 (FIG. 1) for connecting a variety ofperipherals to the portable computer S.

A PCI/ISA bridge 24 is used to connect the PCI bus P and an ISA bus I.Coupled to the PCI/ISA bridge 24 is an IDE interface 26 which connectsto a CD-ROM drive 28 having an IDE controller and to a hard disk drive30. The IDE interface 26 is preferably a busmaster and an IDE/ATAinterface having enhanced IDE features. The CD-ROM drive 28 ispreferably compliant with ATAPI (AT Attachment Packet Interface), theIDE standard for CD-ROM drives, and includes a CD-ROM drive controller102 that is preferably embedded in the CD-ROM drive 28. Also, integratedin the PCI/ISA bridge 24 is a set of programmable interrupt controllers(PIC) 15 for managing hardware interrupts according to their priority.The controller set 15 preferably includes two cascaded PICs for allowinginterrupt channels IRQØ-IRQ15.

Numerous chips which are preferably integrated into the PCI/ISA bridge24 are coupled to the ISA bus I. Both a modem 32 and an audio or soundchip 34 are coupled to the ISA bus I. The sound chip 34 is furthercoupled to an acoustic output device 36 for outputting analog signalssuch as a set of speakers of the computer system S or an external stereosystem. The speakers 36 are preferably audible externally while theportable computer case S is in a closed state. In addition, the soundboard 34 is coupled to the digital master volume control buttons 35 ofthe present invention. Also, a S-IO chip 38 is coupled to the ISA bus I.The S-IO chip 38 provides a parallel port 40, a serial port 42 andconnects to a floppy disk drive 44. To more clearly illustrate thefeatures and operation of the present invention, certain otherconventional computer devices and systems not directly involved in thepresent invention are not shown.

A keyboard controller 46 is also coupled to the ISA bus I. The keyboardcontroller 46 typically connects to a keyboard 48 (FIGS. 1 and 3), aPS/2 port 50, a battery 52, a port 54 coupled to the mini LCD controlcircuitry 810 of the present invention (FIG. 8) for providing controlsignals to a mini LCD screen 55 of the present invention and a powerswitch PWR_SW 58.

The keyboard controller 46 of the present invention includes systemmanagement interrupt (SMW) circuitry for generating system managementinterrupts. Certain processors, such as the Pentium® processor, haveincluded a mode referred to as a system management mode (SMM) which isentered upon receipt of a system management interrupt. A SMI is thesoftware interrupt with the highest priority and is operating systemindependent. Generation of a SMI also causes a SMI handler, which istypically located in a protected memory address space of the system DRAM16, to be executed. A SMI handler is an interrupt service routine forperforming specific system management tasks, like reducing power tospecific devices or providing security services. SMI handler code thusmay be written by one of ordinary skill in the art to perform a varietyof system management tasks.

For the keyboard controller embodiment of the present invention, thekeyboard controller 46 is further coupled to an audio CD mode switchDM_SW 56 (FIGS. 1 and 3) and the audio CD select signal DMSEL. For theCD-ROM drive controller embodiment of the present invention, the CD-ROMdrive controller 102 is coupled to the audio CD mode switch DM_SW 56 andthe audio CD select signal DMSEL. If the power switch DM_SW 58 of thecomputer system S is in an “on” state, the audio CD mode switch DM_SW 56is disabled such that toggling of audio CD mode switch DM_SW 56 has noeffect. The audio CD mode switch DM_SW 56 is also disabled when thecomputer system S in a sleep mode. If the power switch PWR_SW 58 of thecomputer system S is in an “off” state such as a hibernate mode, theaudio CD mode switch DM_SW 56 is enabled.

When the audio CD mode switch DM_SW 56 is enabled, the state of theswitch 56 determines whether the computer system S is in an audio CDmode. The audio CD mode switch DM_SW 56 when placed in an “on” stateserves to place the computer system S of the present invention in anaudio CD mode. Audio CD mode is a secondary operational mode whichenables the computer system S of the present invention to bypasstraditional system BIOS and play audio CDs in a CD-ROM drive 28 withoutrunning an operating system. For further details, reference is made tothe co-pending application, entitled “COMPUTER SYSTEM CAPABLE OF PLAYINGAUDIO CDS IN A CD-ROM DRIVE INDEPENDENT OF AN OPERATING SYSTEM”incorporated above. Also, a status indicator 57 of the present inventionfor indicating when the computer system S is in an audio CD mode iscoupled to the audio CD mode switch DM_SW 56.

When the power switch 58 of a contemporary computer system is placed inan “on” state or the power switch PWR_SW 58 of the computer system S ofthe present invention is placed in an “on” state while the audio CD modeswitch DM_SW 56 is in an “off” state such that the computer system S isin a PC or primary operational mode, the operating system of thecomputer proceeds to access and execute the system BIOS in the BIOS ROM.Executing system BIOS code results in a lengthy booting process whereina power-on-self-test (POST) is performed on the system hardware in thecomputer system. In order to operate a CD-ROM drive in a conventionalcomputer, an operating system must be loaded and a CD-ROM driveapplication initiated such that the device driver of the CD-ROM driveapplication serves as the interface between the CD-ROM drive and theoperating system. The initiation of a CD-ROM application requiressignificant user interaction such as popping up windows and clicking onvarious portions of a computer screen.

Contrastingly, the computer system S of the present invention is capableof avoiding the lengthy boot process associated with contemporary BIOSROM and the significant user interaction associated with a contemporaryCD-ROM drive application by providing an audio CD mode. For the keyboardcontroller embodiment of the present invention, when the computer systemS enters an audio CD mode, the processor-memory subsystem 103, thePCI/ISA bridge 24, the CD-ROM drive 28, the host/PCI bridge 14, theaudio CD mode ROM 60, and the keyboard controller 46 are powered.ROM-based code including code for processing CD button selections isthen loaded from an alternate ROM device, the audio CD mode ROM 60,instead of a conventional BIOS ROM device 62. An operating system is notloaded, thereby significantly reducing the duration of the systeminitialization.

Rather than using a ROM device for conventional BIOS code and a separateROM device for the audio CD code of the present invention, the presentinvention may also be achieved by using a single ROM device. The singleROM device includes a memory address range for conventional BIOS codeand a memory address range for audio CD code 200 of the presentinvention. If the audio CD select signal DMSEL is unasserted, a memoryaddress range for conventional BIOS code is selected. If the audio CDselect signal DMSEL is asserted, a memory address range for audio CDcode 200 of the present invention is selected. Preferably, theconventional BIOS code and the audio CD code 200 share common code suchas POST code. Also, the firmware in the audio CD mode ROM 60 region ispreferably shadowed in the system DRAM 16 to accelerate BIOS accesses.

For the CD-ROM drive controller embodiment of the present invention,when the computer system S enters an audio CD mode, the CD-ROM drive 28and the CD-ROM drive controller 102 are powered. While code is loadedfrom an alternate ROM region for the keyboard controller embodiment, theCD-ROM drive controller embodiment does not require embedded code in analternate ROM region to process CD button selections. Rather, a CD-ROMdrive controller 102 may directly provide CD button selections to aCD-ROM drive 28. Although use of a ROM region is described for bothembodiments, the present invention extends to other non-volatile memorytypes.

Further, when the keyboard controller embodiment of the computer systemS is placed in an audio CD mode, an audio CD select signal DMSEL isasserted and directed to a multiplexer OR gate 64. The multiplexer ORgate 64 receiving the audio CD select. signal DMSEL is coupled to orintegrated into the PCI/ISA bridge 24. If the audio CD select signalDMSEL is unasserted, the multiplexer 64 selects the contemporary BIOSROM 62 by asserting a BIOS control signal, BIOS_CS. If the audio CDselect signal DMSEL is asserted, the multiplexer 64 selects the audio CDmode ROM 60 of the present invention by asserting an audio CD controlsignal, DM_CS.

Referring to FIG. 2, a diagram of the audio CD firmware code 200 in theaudio CD mode ROM 60 is shown. The firmware 200 includes a mini-versionof a power-on-self-test termed quick POST 202, a mini CD-ROM devicedriver 208, a SMI-keyboard controller interface 206, and CD NIT 204, theinitialization code for the mini CD-ROM device driver 208. While aconventional CD-ROM device driver in CD-ROM applications is RAM-based,the mini CD-ROM device driver 208 in the audio CD mode ROM 60 is basedon a non-volatile memory such as read-only-memory (ROM). Also, while theCD-ROM device driver in a conventional CD-ROM application must allow forplaying of audio and data CDs, the mini CD-ROM device driver 208 in theaudio CD mode ROM 60 allows for playing audio CDs, not data CDs, therebyrequiring less code and reducing the execution time for the devicedriver code. If a non-audio CD is present in the CD-ROM drive 28, theaudio CD code opens the door of the drive 28 and generates a beep tosignal to the user that a non-audio CD is present in the drive 28.

In an audio CD mode, a CD button selection is fetched by a keyboardcontroller 46 in a keyboard controller embodiment of the presentinvention. A CD button selection generates an SMI thereby executing theSMI handler code. The SMI-keyboard controller interface firmware 206 isused to pass control from the keyboard controller 46 to the SMI handler.The SMI handler places a keycode which is preferably a bezel buttonvariable corresponding to the selected CD button in a memory area termeda keycode cache. The keycode cache is preferably located in an extendedBIOS data area segment of the SDRAM 16. The SMI handler is also used togenerate a non-maskable interrupt (NMI) which calls the mini CD-ROMdevice driver 208.

In the present invention, a NMI indicates that a bezel button cachecorresponding to a selected CD button is ready to be fetched by the miniCD-ROM device driver 208. The mini CD-ROM device driver 208, which ispreferably a bezel button driver, fetches the bezel button variable fromthe keycode cache. The mini CD-ROM device driver 208 then transmits a CDpacket command corresponding to the bezel button variable to the CD-ROMdrive 28. The CD packet command is preferably a simplified version ofthe Small Computer System Interface (SCSI) command and is used with anATAPI packet command protocol. The drive 28 then issues an interruptrequest (IRQ) which informs the processor 10 that the drive 28 is readyfor execution of the CD packet command. Lastly, the CPU 10 executes theCD packet command. The quick POST firmware 202 performs the necessaryinitialization for the audio CD mode of the computer system S. Forinstance, the quick POST firmware 202 may test for shadow ROM areas,initialize configuration registers, power on the CD-ROM drive 28, poweroff the hard disk drive 30, power down the PCMCIA CardBus controller 18,and initialize the audio chip 34.

A conventional computer system has required a user to access numerouslocations, software and hardware, to adjust the volumes of various audiosources such as a CD, wave, and synthesizer for music listening. Theselocations typically include a mixer in a Windows CD-ROM driveapplication for controlling the volume of audio sources, a softwaremaster volume control in a Windows task bar, and a hardware volumethumbwheel. As these volume control sources controlled volumeindependent of each other, it was necessary for a user to sort throughcumbersome CD-ROM drive software to adjust the volume of the appropriateaudio sources. In light of the software nature of certain volumecontrols, it was also necessary to maintain the portable computer casein an open state with the display screen visible to a user to allow forcertain volume adjustments during music listening.

The present invention eliminates these problems by providing mastervolume control buttons 35 allowing for a single source of volume controlwhich is accessible while the portable computer case C is in a closedstate. The master volume control buttons 35 are digital and arepreferably connected directly to the audio chip 34. The volume up buttonand the volume down button of the master volume control buttons 35 arehardwired inputs to the audio chip 34.

Referring to FIG. 3, a flow chart of the software initialization processfor configuring the computer system S for the master volume controlbuttons 35 of the present invention is shown. At step 300, the softwareinitialization process is initiated by the quick POST firmware 202 whenthe computer system S is being placed in an audio CD mode. Next, controlproceeds to step 302 wherein the audio sources controlled by the CDmixer are set to maximum volume. In this way, the full audio range ismade available for use by the digital volume control buttons 35 when thecomputer system S is in an audio CD mode. Next, in step 306, the mastervolume control buttons 35 of the present invention are initialized. Inthe preferred embodiment, the initialization setting for the mastervolume control buttons 35 is typically about one half, or 50%, of themaximum volume level. From step 306, the software initialization processconcludes at step 308. Thus, the software image for the audio CD mode isset by the quick POST firmware 202 during the system initialization forthe audio CD mode of the present invention.

Referring to FIG. 4, an isometric view of the portable computer case Cwhich contains the computer system S in an open state is shown. Since aconventional CD-ROM drive application was dependent upon an operatingsystem, it was necessary to use a conventional display screen tovisually indicate to a user when a CD-ROM drive application was beingoperated. As such, portable computer users have been required tomaintain a portable computer case containing a portable computer in anopen state to indicate the status of a conventional CD-ROM driveapplication to the user.

In contrast, with the present invention, whether the portable computercase C is maintained in a closed state or open state, a user is capableof determining when a computer system S is in a secondary operationalmode, such as a mode for playing audio CDs in a CD-ROM drive independentof an operating system. The portable computer case C includes a topshell 404 housing a main display screen 406 along with other componentsand a bottom shell 408 housing a keyboard 48 along with othercomponents. The portable computer S of the present invention includes astatus indicator 57 for indicating when the computer system S is in asecondary operational mode. The status indicator 57 (FIGS. 4-6) isprovided on the top surface 410 of the bottom shell 408 of the portablecomputer case C. In the preferred embodiment, the status indicator 57 isprovided near the rear side edge 412 of the bottom shell 408 at alocation near the bottom or rear side edge 414 of the top shell 404. Thelocation of the status indicator 57 and other control switches andindicators on bottom shell 408 is preferably at or near an area 409where the bottom shell 408 and top shell 404 are pivotally connected toeach other to open and close the case C. The edge 414 of top shell 404is recessed or removed at a central portion 405 in the area 407 topermit viewing of the status indicator 57 whether the case C is open(FIG. 4) or closed (FIG. 5). Also, the status indicator 57 is preferablyprovided on an upwardly angled or ramp portion 400 of the top surface410 so that the status indicator 57 may be easily seen by a user. Itshould be understood, however, that other locations on the bottom shell408 which provide convenient viewing for a user may be used.

For a computer system S capable of playing audio CDs in a CD-ROM drive28 independent of an operating system, the status indicator 57 ispreferably a musical note above a circle having a dot in the center ofthe circle or other appropriate icon. The status indicator 57 isprovided to the user on a mini status display screen 55 preferably of aliquid crystal composition. When the computer system S is in an audio CDmode, a pixel pattern corresponding to the icon is displayed on thestatus display screen 55. When the computer system S is in a primaryoperational mode, the icon is not displayed on the status display screen55. Thus, an icon serves as a visual cue to the user. It should beunderstood that the status indicator 57 alternatively may include oneicon for indicating a secondary operational mode and a different iconfor indicating a primary operational mode. An enlarged view of a portionof the top surface 410 of bottom shell 408 of the portable computer caseC is shown in FIG. 6. Thus, it can be seen that the status displayscreen 55 displaying the status indicator 57 is visible to the userwhether the computer case C is open (FIG. 4) or closed (FIG. 5).

The master volume control buttons 35 (FIGS. 1, 4, 5, and 6) of thepresent invention also are preferably located on the top surface 410 ofthe bottom shell 408 of the portable computer case C at or near thelocations described above for the status indicator 57. In this way, auser is capable of adjusting volume control with buttons 35 during asecondary operational mode. This can be done without the need to openthe portable computer case C to visualize on the main display screen 406the CD mixer volume controls for the audio sources. Along with thestatus indicator 57 and master volume control buttons 35 of the presentinvention, other CD control buttons such as play/pause 420, stop 422,previous track 424, and next track 426 are similarly located on the topsurface 410 of the bottom shell 408 of the portable computer case C.

The status indicator 57 and master volume control buttons 35 due totheir location (FIGS. 4, 5, and 6) are visible when the portablecomputer case C is closed (FIG. 5) as well as open (FIG. 4). The audioCD mode control switch DM_SW 56 is also provided on the top surface 410of the bottom shell 408 such that the audio CD mode control switch DM_SW56 is accessible to the user when the computer case C is in an openstate or a closed state.

Referring to FIG. 7, a state diagram of the power control states of theportable computer system S is shown. The power control states arecontrolled by the keyboard controller 46 for the keyboard controllerembodiment of the present invention. The S₁ state is the normal “on”power state of the computer system. The S₁ state corresponds to thepower control switch PWR_SW 58 having a logical state of “1.” In the S₁state, the audio CD mode control switch DM_SW 56 for the secondaryoperational mode computer system is disabled such that toggling theswitch DM_SW 56 has no effect. However, in the S₂ state, the audio CDmode control switch DM_SW 56 is enabled. When the power switch PWR_SW 58is switched to a “0” logical state corresponding to an “off” powerstate, the system is placed in the S₂ power control state. An example ofa power control mode corresponding to the S₂ power control state is ahibernate mode of the computer system S.

In the S₂ state, when the audio CD mode control switch DM_SW 56 isswitched to a “1” logical state, the computer system S is placed in theS₃ power control state. The S₃ power control state corresponds to thenormal power state for a secondary operational mode of a computer systemS such as a mode for playing audio CDs in a CD-ROM drive independent ofan operating system. In the S₃ power state, the processor 10 clockperforms at full speed.

After power up of a secondary operation mode of the computer system Sthe audio CD code places the computer system S in the S₅ power stateusing logic in the PCI-ISA bridge 24. The audio CD code also places thecomputer system S in the S₅ power state after a CD button selection isprocessed. However, when a CD bezel button is being processed, the audioCD code places the computer system S in the S₃ power control state. TheS₅ power state is a power-on-suspend (POS) mode in which the processor10 clock is stopped.

While the computer system S is in an audio CD mode, the system S is ineither the S₃ power state or the S₅ power state. From the S₃ state,toggling the audio CD mode control switch DM_SW 56 to a logical state of“0” returns the computer system to the S₂ state. Also, from the S₃state, toggling the power control switch PWR_SW 58 to a logical state of“1” places the computer system S in the S₁ state. From the S₁ state, thecomputer system S may also be placed in an S₄ state such as the sleepmode of the computer system S. In the sleep mode of the computer systemS, the audio CD mode control switch DM_SW 56 is disabled.

Referring to FIG. 8, a schematic diagram of the mini status displayscreen control circuitry 810 of the present invention is shown. Thecontrol circuitry 810 is coupled between the keyboard controller 46 andthe mini status display screen 55. The keyboard controller 46 is coupledto the audio CD mode switch DM_SW 56 so that the keyboard controller 46may detect the status of the audio CD mode switch DM_SW 56. Based on thestatus of the audio CD mode switch DM_SW 56, the keyboard controller 46provides a plurality of control signals to the mini status displayscreen 55.

In particular, the keyboard controller 46 generates a data signal 806and a clock signal 808 that are communicated to the data inputs of twoshift registers 800 and 802 which are preferably serial-in, parallel-outshift registers. With each cycle or tick of the clock signal 808, theshift registers 800 and 802 either load the data signal 806 or shift thecurrent data in the register. One of the output state signals 812 ofshift register 800 is provided as an input to shift register 802. Theother output state signals 814 of the shift registers 800 and 802 areprovided to the mini status display screen 55 through an LCD connector804 to generate activation signals for segments of the mini statusdisplay screen 55. By using the keyboard controller 86 to generate adata signal 806 and a clock signal 808, only two pins from the keyboardcontroller 46 need to be dedicated to the operation of the mini statusdisplay screen 55. A plurality of the segments correspond to the portionof the mini status display screen 55 for displaying the secondaryoperational mode status indicator 57. Other segments may be used fordisplaying other status indicators such as a battery gauge indicator.Preferably, each of the output state lines 814 of the shift registers800 and 802 to be provided to the mini status display screen 55 areintermittently illuminated. This may be done by leaving the status lines814 modulated with a 60 Hz clock 816, preferably by using exclusive-ORgates to prevent damage to the mini status display screen 55. Also, aninverted clock signal 60 Hz clock 818 is used to modulate the outputs ofthe LCD connector 804.

Thus, a user is capable of viewing a status indicator 57 and accessingmaster volume control buttons 35 and a control switch 56 for a secondaryoperational mode when the portable computer case C is in either its openstate or its closed state. A user, therefore, is not required tomaintain the case in an open state to determine whether the computersystem S is in a secondary operational mode, to place the computersystem S in a secondary operational mode, or to adjust master volumecontrol during a secondary operational mode of the computer system S.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape, materials, components, circuit elements, wiring connections andcontacts, as well as in the details of the illustrated circuitry andconstruction and method of operation may be made without departing fromthe spirit of the invention.

What is claimed is:
 1. A portable computer system adapted forcontrolling a CD-ROM drive in an operating system-independent reducedpower mode, comprising: a CD-ROM drive to play an audio CD in theoperating system-independent reduced power mode of the portable computersystem; a status display screen to display operational status for theCD-ROM drive in the operating system-independent reduced power mode; anda plurality of CD control buttons to control the CD-ROM drive in theoperating system-independent reduced power mode.
 2. The portablecomputer system of claim 1, wherein the operating system-independentreduced power mode comprises an audio CD play mode for playing an audioCD in the CD-ROM drive.
 3. The portable computer system of claim 1,wherein a processor clock of the portable computer system is stopped inthe operating, system-independent reduced power mode.
 4. The portablecomputer system of claim 1, further comprising: a CD-ROM drivecontroller coupled to the CD-ROM drive and the plurality of CD controlbuttons.
 5. The portable computer system of claim 1, wherein theoperating system-independent reduced power mode is a secondaryoperational mode of the portable computer system.
 6. The portablecomputer system of claim 1, further comprising: a means for detecting aselection of the plurality of CD control buttons in the operatingsystem-independent reduced power mode.
 7. The portable computer systemof claim 1, further comprising: a means for directing a selection of theplurality of CD control buttons to the CD-ROM drive in the operatingsystem-independent reduced power mode.
 8. The portable computer systemof claim 1, wherein the status display screen displays an icon toindicate the portable computer system is in the operatingsystem-independent reduced power mode.
 9. A CD-ROM controller for anoperating system-independent reduced power mode of a portable computersystem, the controller comprising: a means for detecting a selection ofa plurality of CD control buttons of the portable computer system in anoperating system-independent reduced power mode of the portable computersystem; and a means for directing the selection to the CD-ROM drive inthe operating system-independent reduced power mode.
 10. The CD-ROMcontroller of claim 9, further comprising: a means for signaling astatus display screen of the portable computer system to displayoperational status for the CD-ROM drive in the operatingsystem-independent reduced power mode.
 11. The CD-ROM controller ofclaim 9, further comprising: a means for detecting a signal for theportable computer system to enter the operating system-independentreduced power mode; and a means for detecting a signal for the portablecomputer system to exit the operating system-independent reduced powermode.
 12. The CD-ROM controller of claim 9, further comprising: a meansfor enabling digital volume control of the CD-ROM drive in the operatingsystem-independent reduced power mode.
 13. The CD-ROM controller ofclaim 9, wherein the operating system-independent reduced power modecomprises an audio CD play mode for playing an audio CD in the CD-ROMdrive.
 14. A method of playing an audio CD in a CD-ROM drive of aportable computer system in an operating system-independent reducedpower mode, the portable computer system including a plurality of CDcontrol buttons, the method comprising the steps of: detecting aselection of the plurality of audio CD buttons in the operatingsystem-independent reduced power mode; and directing the selection tothe CD-ROM drive in the operating system-independent reduced power mode.15. The method of claim 14, further comprising the steps of: detecting asignal for the portable computer system to enter the operatingsystem-independent reduced power mode; and detecting a signal for theportable computer system to exit the operating system-independentreduced power mode.
 16. The method of claim 14, further comprising thestep of: signaling a status display screen of the portable computersystem to display an operational status for the CD-ROM drive in theoperating system-independent reduced power mode.
 17. The method of claim14, further comprising the step of: processing an audio CD by the CD-ROMdrive in response to the CD-ROM drive receiving the selection in theoperating system-independent reduced power mode.
 18. The method of claim14, further comprising the step of: enabling digital volume control forthe CD-ROM drive in the operating system-independent reduced power mode.